ABSTRACT
Heat transfer plays a critical role in industrial combustion processes where the primary objective is to transfer heat from the hot combustion products to some type of load. In industrial processes, radiation is often the dominant mechanism and forced convection also plays an important function. The more efficient the heat transfer processes, the higher the overall system efficiency. This is important for many reasons. The operating costs in the form of fuel are inversely proportional to the efficiency-the higher the efficiency the lower the fuel consumption. Pollution emissions are indirectly proportional to fuel efficiency. The higher the efficiency, the lower the fuel consumption and therefore the lower the emissions per unit of product because less fuel is combusted and therefore less emissions are produced. More efficient processes usually mean that
either the combustors can be smaller for a given production rate, or alternatively, more can be produced in a given size combustor. This means that capital costs may be reduced per unit of product. That also translates indirectly into more emission reductions because less energy is needed to make the combustor and therefore less pollutants are generated in the fabrication process. A smaller combustor per unit of product means that less space is required in the plant. Higher thermal efficiencies usually also mean that less energy is lost through the walls of the combustor, which benefits the workers in the vicinity who will be less likely to be overheated and burned. Improved thermal efficiencies are therefore dependent on maximizing the heat transfer from the combustion products to the load. This is a particular benefit of oxygen-enhanced combustion because of the reduction in nitrogen in the oxidizer, which acts as a ballast to carry heat out with the exhaust products (see Chapter 1).
